Browsing School of Dentistry by Subject "MRI"
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Effect of Maxillary Features on Tongue Anteriority in Glossectomy and Control SpeakersThis study examines the behavior of glossectomy (N = 15) and normal tongue (N =20) movement using combination of high-resolution and cine- MRI. The speech task "a souk" was used to measure anterior tongue displacement, termed "anteriority", from /uh/ to /s/. Effects on anteriority due to palate height, /s/ type, arch perimeter, canine width, and orthodontic extraction of teeth were measured on controls and patients. Results showed that all factors except canine width had no significant difference in anteriority of tongue. Canine width was significantly related to anteriority in an inverse relationship. The fact that arch perimeter is less important than canine width on anteriority is consistent with our understanding of the criticality of the location of the tongue tip, rather than the tongue body, in producing /s/. Data also suggests that less than average arch perimeter improves speech intelligibility in patients with T2 tumor of the tongue.
The Effects of Glossectomy and Palatal Dimension on Activity of the Tongue Muscles: A Quantitative MRI AnalysisPurpose: The purpose of this study was to compare the tongue muscle activity of glossectomy patients and normal controls and to determine which of the following factors - palate height, palate width, and tumor size (T1 vs. T2) - might influence muscle activity after glossectomy. Methods: Muscle shortening within the hemi-tongue of 12 controls and 9 glossectomy patients was measured during the elevation and retraction of the tongue from /s/ into the /uk/ of the word "a souk" using cine-MRI and tagged-MRI. The muscle length measurements were performed on the following five tongue muscle segments: 1) genioglossus posterior (GGp), 2) geniohyoid (GH), 3) transverse anterior (Ta), 4) transverse middle (Tm), and 5) transverse posterior (Tp). Results: The controls demonstrated significant asymmetric Ta and Tp muscle shortening with the larger side shortening more than the smaller side. The patients showed relatively symmetric muscle shortening on the native and the resected sides. High palate subjects showed greater GH shortening, while wide palate subjects showed greater GH and Ta shortening. No significant interaction was found between the effects of palate dimension and glossectomy on muscle shortening. A significant positive correlation between shortening was found in five pairs of muscles in controls' both sides and in one pair (Ta and Tm) in patients' native side. The T2 patients showed less shortening than T1 patients on both the native and the resected sides for Ta and Tm. Conclusion: There were no statistically significant differences in muscle shortening between the controls and the patients, suggesting that patients were unable to adapt to an easier, asymmetric muscle activity as in controls during multiple repetitions of speech task. The effects of palate height and width were independent of the surgical effects. In controls, the muscles functioned synergistically in order to elevate the tongue by decreasing its length and width. In patients, the Ta and Tm worked in concert to decrease tongue width and create a compensatory behavior during tongue elevation. The lesser muscle shortening in T2 than T1 patients suggested greater impairment and limited muscle activity in T2 patients.
Tongue Muscle Shortening Differences in Glossectomy Versus Non-Glossectomy PatientsIn cancers that affect the tongue, the most common treatment is glossectomy, a procedure that can have substantial effects on a patient’s intelligibility. We are seeking to identify the effect of this resection on the use of four muscles – genioglossus, transversus, verticalis, and superior longitudinal, which comprise the bulk of the tongue. MRI data was used to study differences in tongue muscle shortening patterns during the speech task “a thing” between patients who have undergone glossectomies and controls who have not. Speech data was collected from 2D tagged-MRI movies and reconstructed into 3D volumes at 26 timeframes. Velocity fields and tissue points were extracted and shortening was calculated to study how the muscles were used by glossectomies vs. controls to protract and retract the tongue during /θ/. The results reveal differences in function between the two groups, and potential compensation strategies for glossectomy patients.